Type check @abi decls (sans attrs)

This commit compares the decl inside the `@abi` attribute to the decl it’s attached to, diagnosing ABI-incompatible differences. It does not yet cover attributes, which are a large undertaking.

Author: beccadax

include/swift/AST/DiagnosticEngine.h

@@ -702,6 +702,10 @@ namespace swift {
     /// Flush the active diagnostic to the diagnostic output engine.
     void flush();
 
+    /// Returns the \c SourceManager associated with \c SourceLoc s for this
+    /// diagnostic.
+    SourceManager &getSourceManager();
+
     /// Prevent the diagnostic from behaving more severely than \p limit. For
     /// instance, if \c DiagnosticBehavior::Warning is passed, an error will be
     /// emitted as a warning, but a note will still be emitted as a note.
@@ -1560,6 +1564,10 @@ namespace swift {
     }
   };
 
+  inline SourceManager &InFlightDiagnostic::getSourceManager() {
+    return Engine->SourceMgr;
+  }
+
   /// Remember details about the state of a diagnostic engine and restore them
   /// when the object is destroyed.
   ///

include/swift/AST/DiagnosticsSema.def

@@ -8351,16 +8351,16 @@ ERROR(attr_abi_mismatched_kind,none,
 
 ERROR(attr_abi_mismatched_arity,none,
       "cannot give %kind0 the ABI of a %kindonly0 with a different number of "
-      "low-level parameters",
-      (ValueDecl *))
+      "%select{|generic }1parameters",
+      (Decl *, /*genericParams=*/bool))
 
 ERROR(attr_abi_mismatched_throws,none,
       "cannot give %0 the ABI of a %kindonly0 which %select{cannot|can}1 throw",
-      (ValueDecl *, /*abiCanThrow=*/bool))
+      (Decl *, /*abiCanThrow=*/bool))
 
 ERROR(attr_abi_mismatched_async,none,
       "cannot give %0 the ABI of %select{a non-async|an async}1 %kindonly0",
-      (ValueDecl *, /*abiIsAsync=*/bool))
+      (Decl *, /*abiIsAsync=*/bool))
 
 ERROR(attr_abi_mismatched_pbd_size,none,
       "cannot give pattern binding the ABI of a binding with "
@@ -8369,13 +8369,65 @@ ERROR(attr_abi_mismatched_pbd_size,none,
 
 ERROR(attr_abi_mismatched_var,none,
       "no match for %select{%kind0 in the ABI|ABI %kind0}1",
-      (ValueDecl *, /*isABI=*/bool))
+      (Decl *, /*isABI=*/bool))
 
 ERROR(attr_abi_incompatible_with_silgen_name,none,
       "cannot use '@_silgen_name' and '@abi' on the same %0 because they serve "
       "the same purpose",
       (DescriptiveDeclKind))
 
+ERROR(attr_abi_mismatched_type,none,
+      "type %0 in '@abi' should match %1",
+      (Type, Type))
+NOTE(attr_abi_should_match_type_here,none,
+     "should match type here", ())
+
+ERROR(attr_abi_mismatched_generic_signature,none,
+      "generic signature '%0' in '@abi' is not compatible with '%1'",
+      (StringRef, StringRef))
+ERROR(attr_abi_missing_generic_signature,none,
+      "declaration in '@abi' should have generic signature compatible with "
+      "'%0'",
+      (StringRef))
+ERROR(attr_abi_extra_generic_signature,none,
+      "declaration in '@abi' should not have generic signature because %0 "
+      "is not generic",
+      (Decl *))
+
+ERROR(attr_abi_mismatched_param_modifier,none,
+      "%select{default |}0%3 %select{attribute|modifier}2 "
+      "%select{|'%0' }0in '@abi' is not compatible with %select{default|'%1'}1",
+      (StringRef, StringRef, /*isModifier=*/bool, DescriptiveDeclKind))
+ERROR(attr_abi_no_default_arguments,none,
+      "%kind0 in '@abi' should not have a default argument; it does not "
+      "affect the parameter's ABI",
+      (Decl *))
+
+// These macros insert 'final', 'non-final', or nothing depending on both the
+// current decl and its counterpart, such that 'non-final' is used if the
+// counterpart would be described as 'final' or 'static'. They must be kept in
+// sync with `StaticnessAndFinality`.
+#define NONFINAL_OR_NOTHING(COUNTERPART) \
+      "%select{||non-final |non-final |non-final |%error}" #COUNTERPART
+#define FINAL_OR_NONFINAL_OR_NOTHING(CURRENT, COUNTERPART, FINAL_OK) \
+      "%select{|%select{" NONFINAL_OR_NOTHING(COUNTERPART) \
+                      "|" NONFINAL_OR_NOTHING(COUNTERPART) \
+                      "|final |final ||%error}" #CURRENT "}" #FINAL_OK
+
+ERROR(attr_abi_static_final_mismatch,none,
+      FINAL_OR_NONFINAL_OR_NOTHING(0, 2, 4) "%kind1 in '@abi' should be "
+      FINAL_OR_NONFINAL_OR_NOTHING(2, 0, 4) "%kindonly3 to ensure ABI "
+      "compatibility",
+      (uint8_t, Decl *, uint8_t, Decl *, /*isClass=*/bool))
+
+#undef NONFINAL_OR_NOTHING
+#undef FINAL_OR_NONFINAL_OR_NOTHING
+
+ERROR(attr_abi_failable_mismatch,none,
+      "cannot give %select{non-failable|failable}1 %kind0 the ABI of a "
+      "%select{non-failable|failable}2 %kindonly0",
+      (Decl *, bool, bool))
+
 //===----------------------------------------------------------------------===//
 // MARK: Isolated conformances
 //===----------------------------------------------------------------------===//

lib/Sema/CMakeLists.txt

@@ -50,6 +50,7 @@ add_swift_host_library(swiftSema STATIC
   TypeOfReference.cpp
   TypeCheckAccess.cpp
   TypeCheckAttr.cpp
+  TypeCheckAttrABI.cpp
   TypeCheckAvailability.cpp
   TypeCheckBitwise.cpp
   TypeCheckCaptures.cpp

lib/Sema/TypeCheckAttr.cpp

@@ -195,68 +195,10 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
   IGNORED_ATTR(Unsafe)
 #undef IGNORED_ATTR
 
-private:
-  static unsigned getABIArity(AbstractFunctionDecl *afd) {
-    unsigned arity = afd->getParameters()->size();
-    arity += afd->getGenericSignature().getGenericParams().size();
-    if (afd->hasImplicitSelfDecl())
-      arity += 1;
-    return arity;
-  }
-
-  void checkABIAttrPBD(PatternBindingDecl *APBD, VarDecl *VD) {
-    auto PBD = VD->getParentPatternBinding();
-
-    // To make sure we only diagnose this stuff once, check that VD is the first
-    // anchoring variable in the PBD.
-    bool isFirstAnchor = false;
-    for (auto i : range(PBD->getNumPatternEntries())) {
-      auto anchorVD = PBD->getAnchoringVarDecl(i);
-      if (anchorVD) {
-        isFirstAnchor = (anchorVD == VD);
-        break;
-      }
-    }
-
-    if (!isFirstAnchor)
-      return;
-
-    // Check that the PBDs have the same number of patterns.
-    if (PBD->getNumPatternEntries() < APBD->getNumPatternEntries()) {
-      diagnose(APBD->getPattern(PBD->getNumPatternEntries())->getLoc(),
-               diag::attr_abi_mismatched_pbd_size, /*abiHasExtra=*/false);
-      return;
-    }
-    if (PBD->getNumPatternEntries() > APBD->getNumPatternEntries()) {
-      diagnose(PBD->getPattern(APBD->getNumPatternEntries())->getLoc(),
-               diag::attr_abi_mismatched_pbd_size, /*abiHasExtra=*/true);
-      return;
-    }
-
-    // Check that each pattern has the same number of variables.
-    for (auto i : range(PBD->getNumPatternEntries())) {
-      SmallVector<VarDecl *, 8> VDs;
-      SmallVector<VarDecl *, 8> AVDs;
-
-      PBD->getPattern(i)->collectVariables(VDs);
-      APBD->getPattern(i)->collectVariables(AVDs);
-
-      if (VDs.size() < AVDs.size()) {
-        for (auto AVD : drop_begin(AVDs, VDs.size())) {
-          AVD->diagnose(diag::attr_abi_mismatched_var,
-                        AVD, /*isABI=*/true);
-        }
-      }
-      else if (VDs.size() > AVDs.size()) {
-        for (auto VD : drop_begin(VDs, AVDs.size())) {
-          VD->diagnose(diag::attr_abi_mismatched_var,
-                       VD, /*isABI=*/false);
-        }
-      }
-    }
+  void visitABIAttr(ABIAttr *attr) {
+    TypeChecker::checkDeclABIAttribute(D, attr);
   }
 
-public:
   void visitExecutionAttr(ExecutionAttr *attr) {
     auto *F = dyn_cast<AbstractFunctionDecl>(D);
     if (!F)
@@ -295,81 +237,6 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
     }
   }
 
-  void visitABIAttr(ABIAttr *attr) {
-    Decl *AD = attr->abiDecl;
-    if (isa<VarDecl>(D) && isa<PatternBindingDecl>(AD)) {
-      auto VD = cast<VarDecl>(D);
-      auto APBD = cast<PatternBindingDecl>(AD);
-
-      // Diagnose dissimilar PBD structures.
-      checkABIAttrPBD(APBD, VD);
-
-      // Do the rest of this checking on the corresponding VarDecl, not the
-      // PBD that's actually in the attribute. Note that `AD` will become null
-      // if they're too dissimilar to match up.
-      AD = APBD->getVarAtSimilarStructuralPosition(VD);
-    }
-    // TODO: EnumElementDecl?
-
-    if (!AD)
-      return;
-
-    // Check the ABI decl and bail if there was a problem with it.
-    TypeChecker::typeCheckDecl(AD);
-    if (AD->isInvalid())
-      return;
-
-    // Do the declarations have the same kind, broadly speaking? Many kinds have
-    // special mangling behavior (e.g. inits vs normal funcs) that make it
-    // unrealistic to treat one kind as though it were another.
-    if (D->getKind() != AD->getKind()) {
-      // FIXME: DescriptiveDeclKind is overly specific; we really just want to
-      //        say that e.g. a `func` can't have the ABI of a `var`.
-      diagnoseAndRemoveAttr(attr, diag::attr_abi_mismatched_kind,
-                            D, AD->getDescriptiveKind());
-      return;
-    }
-
-    if (isa<AbstractFunctionDecl>(D)) {
-      auto AFD = cast<AbstractFunctionDecl>(D);
-      auto AAFD = cast<AbstractFunctionDecl>(AD);
-
-      // FIXME: How much should we diagnose in IRGen for more precise ABI info?
-
-      // Do the declarations have roughly the same number of parameters? We'll
-      // allow some fuzziness for what these parameters *are*, since there isn't
-      // always an ABI difference between e.g. a free function with N parameters
-      // and an instance method with N-1 parameters (plus an implicit `self`).
-      if (getABIArity(AFD) != getABIArity(AAFD)) {
-        diagnoseAndRemoveAttr(attr, diag::attr_abi_mismatched_arity,
-                              AFD);
-      }
-
-      // Do the declarations match in throwing behavior? We don't care about
-      // `throws` vs. `rethrows` here, just whether callers will account for an
-      // error return.
-      // FIXME: Typed throws?
-      if (AFD->hasThrows() != AAFD->hasThrows()) {
-        diagnoseAndRemoveAttr(attr, diag::attr_abi_mismatched_throws,
-                              AFD, /*abiCanThrow=*/AAFD->hasThrows());
-      }
-
-      // Do the declarations match in async-ness?
-      if (AFD->hasAsync() != AAFD->hasAsync()) {
-        diagnoseAndRemoveAttr(attr, diag::attr_abi_mismatched_async,
-                              AFD, /*abiHasAsync=*/AAFD->hasAsync());
-      }
-    }
-
-    // TODO: Diagnose if Protocol::isMarkerProtocol() - contradiction in terms
-    //       (and mangler can't handle invertible protocols with @abi)
-
-    // TODO: Validate more
-    // FIXME: The list of properties that have to match is practically endless
-    // and will grow as new features are added to the compiler. We might want to
-    // write an AttributeVisitor just to help us catch omissions over time.
-  }
-
   void visitAlignmentAttr(AlignmentAttr *attr) {
     // Alignment must be a power of two.
     auto value = attr->getValue();